The present invention relates to photographic processing equipment. In particular, the present invention relates to an improved paper feed control system for use in an automatic photographic paper cutter.
In commercial photographic processing operations, very high rates of processing must be achieved and maintained in order to operate profitably. To expedite the photographic processing, orders containing film of similar type and size are spliced together for developing. As many as 500 to 1000 rolls of 12, 20, and 36 exposure film may be spliced together for processing and printing purposes.
After developing, the photographic images contained in the film negatives are printed in an edge-to-edge relationship on a continuous strip of photosensitive paper by a photographic printer. The photographic printer causes high intensity light to be passed through a negative and imaged on the photographic print paper. The photographic emulsion layer on the print paper is exposed and is subsequently processed to produce a print of the image contained in the negative.
After the strip of print paper has been photoprocessed to produce prints, a photographic paper cutter cuts individual prints from the strip. The prints are then sorted by customer order and ultimately packaged and sent to the customer.
Automatic print paper cutters have been developed which automatically cut the print paper into individual prints. These automatic paper cutters are controlled by indicia which are placed along the print paper by the photographic printer. Typically the indicia are of two types: cut marks and end-of-order marks. The cut marks indicate the desired location of a cut between adjacent prints. The end-of-order marks, which typically appear along the opposite edge of the print paper from the cut marks, indicate the end of a customer's order. The automatic paper cutter includes a sensor which senses the cut mark and causes the individual prints to be cut from the strip at the desired locations. The separated prints are passed to an order packaging or grouping device, which groups the prints in response to the end-of-order marks which are sensed by the automatic cutter.
In the prior art automatic paper cutters, the cut mark sensor has been movable along an axis parallel to the paper feed path. The prior art systems have required that the operator position the cut mark sensor at a distance greater than the length of one print from the paper cutter knife. The sensor, therefore, is positioned two cut marks upstream from the knife assembly. When the sensor senses a cut mark, the paper feed is stopped and the paper is cut at a location indicated by the cut mark from the previous paper feed cycle, not the cut location indicated by the cut mark just sensed.
The prior art arrangement has several significant disadvantages. First, it requires the operator to make highly sensitive adjustments to the position of the sensor each time different size prints are to be cut. This is particularly difficult since the knife assembly, for safety reasons, is generally a closed structure. The operator, therefore, must guess on the precise location of the cut mark sensor. The only way that the operator can be certain that the cut mark sensor is in the proper position, is to run repeated tests and readjust the sensor position, if necessary, until the cuts are being made at the correct locations. This operation wastes time and print paper, and is highly operator dependent.
Second, because the cut mark sensor is sensing a cut mark associated with a different cut location from the location then being cut by the knife assembly, inaccurate operation results if the print length varies. The prior art system assumes that all prints on the strip will have equal lengths and that, therefore, it is possible to sense cut marks one or more prints upstream from the knife assembly.